We propose to isolate behavioral mutants of zebra fish (Brachydanio rerio). We have developed methods for producing homozygous diploid fish. We propose to treat females from clones of homozygous fish with a mutagen, and to generate homozygous diploid progeny from eggs of such females. Individuals that develop with be screened for abnormal optomotor responses. Clones will be derived from fish with abnormal responses and members of such clones will be subjected to the appropriate behavioral, anatomical, physiological, developmental and genetic analysis. Priority will be given in these studies to mutants that exhibit altered retinotectal connections.